Dust collector screen



DEC. 8, 1931. DORFAN 1,835,475

DUST COLLECTOR SCREEN 7 Filed May 1, 1929 4 Sheets-Sheet 1 in II III III Dec. 8, 1931. M. l. DORFAN DUST COLLECTOR SCREEN '4 Sheets-Sheet 2 Filed May 1, 1929 Dec. 8, 1931 MILDORFAN 1.835.475

DUST COLLECTOR S GREEN Filed May 1, 1929 4 Sheets-Sheet 3 13 my v J 1;

80 wue/niow LA" or MA,

Dec. 8, 1931. DQRFAQ I 1,835,475

DUST COLLECTOR SCREEN Filed May 1. 1929 4 Sheets-Sheet 4- Patented Dec. 8, 1931 UNE'EEE) STATES llIORTON I. DOB-FAN, OF HAG-ERS'IOWN, MARYLAND, ASSIGI'IOR TO IANGBORN COR- PORATION, F HAG-ERSTOWN, MARYLAND, A CORPORATION OF MARYLAND DUST COLLECTOR SCREEN lip lication filed May 1, 1929.

According to the formerly existing practice, dust collector screens have been made by wrapping a strip or web of cloth about a rectangular wooden frame, the clotli heing permanently secured on all four sides by tacking, gluing or other means so that 1f any portion of the cloth became worn or must be removed for any purpose, the entire covering must be stripped from the frame and the n cloth could hardly be removed without destroying the frame itself.

lVhile the clear air side is inside the screen,

a certain amount of dust passes through the cloth and is deposited at this point, i. e., within the screen at the bottom beneath the two layers of cloth on the opposite. sides of the frame. In the course of time this accumulation becomes considerable and in accordance with the former practice, it could only be removed by removing the frame from the assembly. Another difliculty with the former construction resides in the fact that from time to time, due to shrinking, setting or warping of the wood forming the frame or to 26 the fact that the cloth in use takes up a heavy load of dust, increasing the weight of the cloth and causing it to sag, or for other reasons, the cloth tends to loosen and this loosening of the cloth interferes with the operation of cleaning the screens. In thisconnection it will be understood that, in accordance with the present practice, cleaning is accomplished by vibrating the screens, which vibration of the screens is not efiective to vibrate and clean the cloth unless the cloth is reasonably tight. Accumulation of dust on the cloth also causes loss of pressure in forcing the air through the screens, and, by increasing the resistance of the cloth, the accumulation of dust increases the tendency of the cloth to stretch by increasing the pressure to which the cloth is subjected in forcing the air through it.

Tightness of the screen cloth is also necessary to prevent the collapsing of the cloth which tends to close the air passages between the layers of cloth, particularly the clear air passages, and thus interfere Wlltll the proper filtering of the air. It is also of interest that the bulk of the wear ordinarily Serial No. 359,503.

affects the cloth on one side of the screen, i. e., thcside from which the inflowing dust laden air comes so that it is desirable to have the screen so constructed that the cloth on either side can be renewed without changing and renewing that on the other side.

The object of the present invention is to provide a new and improved dust collector screen involving-new features and details of construction whereby the above described and other difficulties in the filtration of air are overcome.

In accordance with the improved construction, the screen cloth is so secured that it may be conveniently removed and replaced, preferably the cloth on each side of the individual screen frames is separate from that on the other side so it can be separately removed, and the bottom edges of the cloth on the two sides of the frame are so'fastened that they may be disengaged by a single operation without removing the screen from the assembled'dust collector structure providing for the easy, convenient and almost instantaneous discharge of any accumulation of dust which may occur on the clear air side, i. e., between'the two layers of cloth on the opposite sides of the individual screens or screen frames. The improved structure also provides in the preferred form an easy and convenient, cheap and quickly operable and removable sealing means for connecting the adjacent screens at the front, i. e., the clear air discharge side, and it further includes means for adjusting the frame to take up the slack and tighten the cloth without removing the individual screens from the assembled dust arrester, when and if it becomes loosened through any of the causes above named or in any other manner and numerous other improved features and details to be more fully hereinafter described.

In the accompanying drawings I have illustrated a dust collector screen embodying the features'of my invention in the preferred form. I have also illustrated diagrammatically and otherwise a dust collector assembled, showing the manner of using the screen.

In the drawings:

Figure 1 is a side elevation of a single dust collector screen, portions of the cloth being removed to expose the frame structure normally covered thereby.

Figure 2 is an elevation of the same looking at the screen from the right as seen in Figure 1, i. e., from the discharge side or edge of the screen.

Figure 3 is a section on an enlarged scale taken on the line 3-3 in Figure 1, the screen being broken away intermediately to reduce the length of the figure for convenience of illustration.

Figure 4 is a fragmentary section on the same plane as Figure 3, but on a slightly smaller scale, showing the bottom end of the adjusting rod and convenient manner of en gaging the same by means of a socket wrench.

Figure 5 is a section on the same scale as Figure 3 and on the line 5'5, Figure 1, showing a cross section of the top member of the frame and the manner of securing the cloth thereto.

Figure 6 is a section on the line 6-6, Figure 1, but showing instead of a single screen the manner of arranging and connecting several screens at the front. i. e., the clear air side, as in the assembled dust collector.

' Figure 7 is a section on the line 77 Figure 1, showing the corner construction and the manner of connecting the frame members at this corner.

Figure 8 is a section on the line 8-8 of Figure 1 showing the arrangement of the frame member on the left hand side of the screen in said Figure and the manner of securing the cloth thereto, this being the rearward or dust side of the assembled dust collector.

Figure 9 is a bottom plan view of a single screen as shown in Figures 1 and 2.

Figure 10 is an elevation on a reduced scale looking at a single screen member from the side opposite to that from which the view, Figure 1, is taken.

Figure 11 is a perspective view of the assembled dust collector having the screens of the invention. the outer casing being removed and the screens being cut away on a horizon tal plane spaced upwardly from the bottom of the screens about one third of their height.

Figure 12 is a diagrammatic view showing a dust collector system in plan, the same being provided for convenience in describing the manner of assembling and operating the screens.

Referring to the drawings by numerals, each of which is used to indicate the same or similar parts in the different figures, the dust collector assembly illustrated in. the diagrammatie view, Figure 12, includes a casing 1, having an air inlet 2 on the dustside, which inlet is connected to the various sources of dust laden air to be filtered, which are indicated in the form of abattery of tumblers or tumbling mills 3, and a battery of grinders suitably encased in guards 4, the tumblers and grinders being connected by branch pipes 5, 6 to the air inlet 2. The illustration also includes an eXhauster 7 connected by an exhaust pipe 8 to the clear air side of the dust arrester 9 and having a discharge pipe 10 discharging the cleaned air back into the building, 11, the casing 1 and the dust arrester apparatus being preferably located outside the building. This is mainly to save floor space and is not material.

The dust collector 9 consists of a series of dust collector screens 12 assembled in any suitable manner, a convenient arrangement being shown in Figure 11. The individual screens 12 consist each of an open frame 1%, which is preferably rectangular, and covered on its respective sides by layers of cloth 15-16, closing the opening and spaced apart by an interval which corresponds to the t iickness of the frame. The screens 12 are, in turn, shown in the assembled dust collector as placed with the respective frames 14 in registration. The screens are shown as spaced apart so as to provide an opening 17 on the inlet or dust side between each adjacent pair of screens. The corresponding space 18 on the clear air side or edges of the screens is, in the form of the invention shown, reduced by a shouldered strip or spacer 19 to be more fully described, the remaining space 20 between the screens on the clear air side being closed by means of any suitable flaps 21 which may be overlapped and secured to the spacer strips 19 or any suitable and available portion of the screen frame. There is also a clear air outlet for each screen on the clear air side provided in the form of the invention shown by the slots 13 in the upright frame member 27 to be described, on the clear air side of each screen. and parallel to the cloths 15 and 16.

The screens are shown as pivotally mountedat the bottom as by means of pins 24-. having suitable bearings in an angle support 25, the opposite corners of the screens at the bottom being free to rock on the bottom rail 22 of a screencrib 28 in which the screens are enclosed on the clear air side or edges. The screens thus supported are vibrated in a direction normal to the cloth an d in any suitable manner, illustration of which is not necessary to the present invention, in order to dislodge the dust which is deposited on and in the fabric.

Referring more specifically to the details of the screen structure, each individual screen member 12 consists of a frame 14- which is preferably rectangular and made of wood or any suitable material, the frame 14: being covered on its opposite rectangular faces, already stated, by layers of cloth 15-16, which are preferably separate. The frame 14 in the form of the invention shown consists of a top bar 25, a single side bar 26 on the inlet or dust side or edge, a slotted side bar These slots are between 7 2'? on the clear air side or edge, the members 2627 being upright, and the member 25 horizontal or nearly so, and a bottom bar 8 wiich is also preferably horizontal or nearly so.

The top bar 25 is shown, see the section Figure 5, in the form of a solid member grooved longitudinally on each lateral face at 80 and 31, respectively, said grooves serving to assist in holding the separate screen cloths 1516 at their respective top edges, the cloth being laid in the grooves and held by means of removable fastening strips 32 and 33, which are laid over the cloth and forced into the grooves, carrying the cloth with them as shown and the strips are in turn removably secured in any suitable manner as by means of screws 34. The top bars are also shown as scored transversely at intervals on three sides, i. e., on the top and lateral surfaces, to receive the vertical supporting wires 35, which are laid in the scores and looped around the bar, the scores indicated by refcrence character 36 being best illustrated in Figure 1. The top bar is also shown as having a vertical hole or bore 88 near the center which receives the top end 89 of an adjusting rod 40.

The top bar 25 is secured at its end which is at the right in Figure 1, to the upright 27 in any suitable manner, the construction which has been so far employed being shown in Figure 7. In accordance with this construction, the end of the top bar 25 is rabbeted at 42, 42 to receive vertical strips 43 and it which form the upright 27. These strips are thus spaced apart by the top mem ber 25 reduced by rabbeting 42 as described, and glued and otherwise connected as by means of screws 45 also holding the strip 19 at the top and screw 46 holding the fastening slrip 4? at the top.

It will be understood that the frame members 28 and 25 are preferably composed of wood and the joints at the respective corners are sufliciently elastic to provide a slight degree of yield and expansion of the frame in response to the outward pressure applied by means of the adjusting rod 40 as hereinafter described, and this expansion of the frame 14 serves to take up the screen cloths and the wires 35 particularly at the center where the tendency to yield is the greatest. The yielding of the cloth and wires, which is suficient to so loosen the cloth as to greatly reduce the eiiiciency of the apparatus is very slight and is easily taken up in this The structure shown and described has been used quite extensively in a commercial way, the patent ollice drawings being made from the working drawings of the commercial article, and is found to operate with complete satisfaction in pratice.

At the other end, the top bar 25 is secured to the solid upright 26 in any suitable manner not illustrated in detail. The upright side bar 26 in the preferred arrangement of the screen shown, said upright 26 being in the form of the invention shown, incidental to the preferred construction at the dust side of the screen, is a solid member grooved longitudinally and hence vertically at l8 and 49, on its opposite faces which aresubstantially parallel to therespective planes of the cloths 15 and 16. These grooves 48 and 19 are utilized, as are the grooves 30 and 31 in the top bar, to receive and locate the removable strips, preferably metal strips, 50 and 51, which, in turn, removably secure the corresponding vertical edges of the screen cloths 15 and 16, the strips being held by suitable removable fastening means as screws 52 and 53. The member 26 is secured at its lower end to the bottom bar 28. In the arrangement of the device shown, this solid bar 26 comes at the left end of the bottom bar 28 as seen in Figure 1. This joint and all the corner joints of the frame may be made in accordance with the well known practice in making window frames, screens or the like, or in any suitable manner. In Figure 1, this end of the bottom bar 28 is shown as provided with a metal clip or bracket 54, which supports the corresponding journal pin 24.

The bottom bar 28 is shown as scored transversely at intervals at 55 on three sides, i. e., the bottom and the two lateral sides, to receive the supporting wires 85 and it is also bored at 56 to admit the lower end of the adjusting rod 40 to be described, the aperture or bore 56 being shown as enlarged at the lower end at 57 to admit a socket wrench 58. An important feature of the bottom bar 28 consists in the provision of removable means, preferably a single means, for holding the bottom edges of the respective screen cloths 15 and 16. In the form shown, the bottom bar is grooved as to its bottom surface for substantially its entire length at 58, and this groove receives a holding strip 59, preferably of metal, which, in operation, covers the edges 6061 of the cloths which are placed across the groove, the strip and edges of the cloth being forced into the groove and the strip rcmovably secured in any suitable manner as by means of screws 62. The bottom bar 28 is secured at its right hand end as seen in Figure 1, to the slotted upright 27 in any suitable manner not specifically illustrated, the arrangement Figure 7 being suitable.

The tension rod e0 previously referred to extenos across the screen near the lateral center and from top to bottom, being shown as threaded at both ends at 63 and provided at each. end with a suitable nut (i l-65 engaging the thread, the nut being innnediatcly be low the top bar and the nut 65 immediately above the bottom bar 28. The. threads on the endsof the rod 40 may be of any suitable form, being shown. as right-handed These nuts as shown rest on Washers 66, which, in turn, rest on the top and bottom bars respectively. Preferably, the top nut 64: is held in fixed position in any suitable manner as by tightening it against the bottom of the end of the top thread before the cloth is applied. The bottom nut 65 when the parts are under tension, is held against rotation by contact with the washer 66 and contact of the washer 66 with the bottom bar 28. The bottom nut may be adjusted to tension the screw, by freeing a portion of the cloth at the bottom and engaging the nut with a suitable wrench. In ac ZUliittHC-Q with the preferred operation of the form illustrated, however, the frame is adjusted and the wires 35 and the screen cloths l5 and 16 are tensione from the bottom without remoting the screen from the dust collector assembly. For this purpose the fastening strip 59, is apertured, a small portion of theclothbeingpreferably removed as shown to give access to the socket 57. The socket wrench 58 provided for this purpose, is suitably bored and threaded to engage tie lower thread 63 on the rod l0. This is inserted in the opening 57 and screwed up on the rod until the end of the rod contacts the bottom of the socket, the wrench being then further rotated, turns the rod relatively to the nut 65. the nut 64 turning with the rod. Ordinarily, this adjustment is most effectively utilised to tighten the screen cloth and, for this purpose, in the form of the invention shown, the rod is turned in righthanded rotation as seen from the bottom end. In fact, this wrench cannot be used to rotate it in the opposite direction as loosening of the cloth is not desirable.

The supporting wires already referred to provide a resilient and flexible support for the screen colths. These wires if employed, or any equivalent means substituted therefor, may be arranged in any preferred manner. in the form of the invention shown, these wires extend from the top bar 25 to the bottom bar 28, being placed at suitable intervals between the side bar 26 on one side and the side bar 27 on the other side, preferably in a manner substantially as illustrated in Figure 1. in the form of he invention shown the are placed in pairs, one on each side of the frame and set inward slightly from the outer surface as provided by the scores 36 and 55, see Figure 3, and each pair of wires is shown as formed of a single piece of wire. In accordance with the preferred form illustrated, referr ng particularly to Figure 3, each piece of wire is passed about the bottom si of the bottom bar 28, being seated in the corresponding score 55, one of its ends being passed over the top of the top bar 25 in the corresponding groove 36. These two ends 70 and 71 are then brought together as shown at 69, and joined. The wires are preferably not so tightened as to apply to them the. ultimate tension which they will resist prior to breaking, and yielding of the wires may be provided for by inserting a thin instrument between the wires when twisted, forming an elongated loop 69 which is flattened in yielding. These supporting wires 35 are, in turn, shown as supported at intervals intermediate their length by intermediate cross bars 72, preferably of wood. These cross bars are inserted at one end in the slot 13 in the upright 27, being reduced at this end for this purpose, and they are secured at their opposite ends in and to the solid upright 26 by morticing or in any suitable manner, the width of the bars intermediate their length as shown in Figure 3 being suificient to occupy the space between the members of the pairs of wires 35, so as to provide a support for the same, and in the form of the. invention shown the middle cross bar 73 is of extra width in a vertical direction though neither the exact shape and arrangement of these bars nor their presence in the structure is material to the invention in its broader conception. Strips 43 and 4% are further supported in the position shown and the width of slot 18 is maintained by spacers 13 which are preferably of circular cross section, and apertured to receive screws 46 which hold them.

The screen cloth 16 is secured to the slotted upright 27 by means of the spacing strip 19 already described, which spacing strip is removably secured to the upright, extending substantially the entire length of the same by any suitable and removable fastening as wood screws, 74;.

Preferably, the upright 27 is rabbeted, providing a vertical offset or shoulder at 7 5 in termediate its width on the side which is nearest the observer in Figure 1, the rabbet being in that view concealed by the strip 19 and the strip 19 is correspondingly rabbeted or shouldered at 76 so that when the edge of the cloth is caused to overlie the rabbet or shoulder and the strip 19 is placed on this edge and forced down by the screws 74. the opposed shoulders 75 and 7 6 assist and cooperate in holding the cloth.

The strip 19 in the preferred structure shown is also rabbcted or shouldered as to its edge surface 77, which is outside and at the right in Figure 1 and Figure 6. forming a shoulder 78 which, with the adjacent edge 79 of the strip 1st of the upright 27, forms a vertical groove in the free air edge or side of the screen frame. This groove receives a removable fastening strip 80, preferably of metal. In the preferred form of the invention shown, the free edge of the cloth 15 on the free air edge of the screen is doubled or otherwise a sufliciently strong flat is provided, and to connect the screens in the assembled position illustrated fragmentarily in Figure 6, this doubled edge orflap 21 is placed under the strip and removably secured to the spacer 19 of the next screen connecting the screens together and preventing the escape of the dust laden air on the free air side of the screen, at the same time permitting and providing for vibration of the screens which is transmitted to them for the purpose of cleaning the cloths and dislodging the dust therefrom as previously outlined, the vibratlng means no t of the present invention. The edge 21 of cloth 16 is also placed in the groove beneath flap 21.

The manner of using and operating the screen has been quite fully described in connection with the description of the structure. T he screen cloth-s 15, 16 on the opposite sides of the frame, while they may be arranged to suit the conditions presented, are preferably separate and separately and removably secured at the top and at each side, the bottom edges of both cloths being removably secured at the bottom by means of a single removable strip By virtue of this construction the bottom edges of cloths 15 and 16 can be released by removing the strip 59 which is held by means of screws or in any suitable manner, and any dust which has collected between the clothsfi. e., inside of the screen on the clear air side of the cloths, it being understood that more or less dust works through the cloths from time to time, can be thus conveniently rendered accessible and removed without removing the screen from the assembly shown in Figures 11 and 12.

It will also be apparent that either one of the cloths 15 or 16 can be removed and replaced witl'iont removing the cloth on the her side of the frame or inj u 'ing the frame struc'ure by merely removingthe corresponding strips or 33 at the top, 50' or 51 at the lde, strip 19 or 47 at the clear air side the single bottom strip 59. An advanage nciuent to making the cloths on the two i f the screen separate is apparent from i des ()1.

fact that the cloth on one side nearest to mm which the dust laden air is pre- C for cleaning, i. e., as at the left in F igure 12, is more subject to wear than the cloth on the other side so that a considerable saving is effected by changing the cloths separately.

When and if the cloth becomes loose as the result of long operation, increased Weight due to accumulation of dirt or increased resistance to air pressure, or for any reason, so that it interferes with cleaning the cloth and dislodging the dust by vibration, it may be tightsued by means of the adjusting rod 40, moving the nut 65 away from the vertical center of the rod, forcing the top and bottom members apart. In this connection it should be understood that the nut 64 is stationary,

being turned down against the end of the thread 63 at the top as previously stated on page 11. This adjustment also aifects the wires, the nature and manner of connecting which as shown in a general way in Figure 3 provides for alimited amount of elongation, the wires themselves being somewhat elastic.-

The adjustment of the frame by means of the nut '65 and rod 40 may be effected to tighten the cloth and Wire from the bottom as described by means of the socket wrench 58 when the dust arrester is assembled as shown in Figures 11 and 12, or by means of a wrench on the screen cloth is partially or wholly removed or before it is applied. Normally the nut 64 is tightened before the cloth is applied. V I i V The removable spacing strip 19 and the manner of removably connecting and sealing the screens at the clear air side by means of flaps 21 which are preferably double, and fastening strips 80, provide a most convenient and effective means for sealing the screens at this point, making it possible to disconnect and remove instantaneously any one of the screens forming the dust collector assembly Without disturbing any of the other screens except as to the sealing flaps of those immediately adjacent on one side.

I have thus described specifically and in detail a dust collector screen embodying the features of my invention in the preferred form in order that the nature and operation of the same may be fully understood, how ever, the specific terms herein are used descriptively rather than in a limiting sense, the scope of the invention being defined in the claims.

What I claim as new and desire to secure by Letters Patent is:

1. The combination in a dust collector of a frame, screen cloths, means for securing said screen cloths to the opposite sides of the frame, means for supporting the frame in a dust arrester assembly and means for adjusting the frame to change the area thereof to regulate the tension of the cloth, said means comprising a compression member between the cloths and between the opposite sides of the frame and means for adjusting the effective length of said compression member, said frame being adapted to, give access to the said adjusting means providing for the expansion of the frame and the adjusting of the tension of the cloth in the assembled condition of the dust collector.

2. The combination in a dust collector of a frame, screen cloths, means for securing said screen cloths to the frame on opposite sides of the frame, means for supporting the frame in a dust collector assembly and means for adjusting the frame to change the area thereof to regulate the tension of the cloth, said means comprising a rod extending across the frame between said cloths, an abutment on the rod bearing on the screen frame from the inside, means having a threaded engagement With the rod and bearing on the frame near the opposite end of the rod, said means and rod providing relatively rotatable members the frame being apertured at the end of the rod and in the direction of the length of the rod providing for the insertion of a tool, for rotating one of said rotatable members while the screen is in its assembled position in the dust arrester to perform said adjustment.

3., The combination in a dust collector screen of a substantially rectangular open frame, means for securing the screen cloth to the frame to cover the opening and means for adjusting the area of the opening to determine the tension of the cloth comprising a rod extending across the frame and having an abutment at one end engaging one side of the frame from the inside, the other end of the rod being threaded, and having a nut thereon engaging the other side of the frame from the inside, means for supporting the screen in an assembled dust arrester and means for engaging the rod from outside the screen in the assembled position of the screen to rotate the rod relatively to the nut to change the area of the frame and regulate the tension of the cloth.

4. The combination in a dust collector, screen of an open frame, screen cloth on the opposite sides of the frame and means for removably securing the cloth to, the opposite sides of the frame, comprising removable means to be secured to the frame correspond ing to each of three edges of the cloth and adapted to hold the cloth on each of said three sides and a single means for removably securing the cloths of both sides at the bottom, comprising a single strip adapted to cover and hold both edges and means for securing said strip to the frame covering said edges.

5. The combination in a dust collector screen of an open frame, means for securing screen cloth to the frame to cover the opening on both sides and means for removably securing both bottom edges of the cloth, said securing means being located on the bottom side of the bottom frame member, means for supporting the screen in a dust collector assembly, said means securing the bottom edges of the screen cloth being accessible from belowand removable in the assembled condition of the dust collector.

6. The combination in a dust collector of a purality of screens, each having an open frame, said frame including a bottom frame member, screen cloth covering both sides of the frame and a single means for securing the screen cloth on both sides at the bottom, comprising a strip located on the bottom side of the bottom frame member, and adapted to cover the bottom edges of the cloth on both sides of the frame and means for removably securing the strip, said means and said strip being accessible and removable in the assembled condition of the dust collector.

7. The combination in .a dust collector screen of an open frame with screen cloth covering both sides of the frame and a single means for securing the screen cloth of both sides at the bottom, comprising a strip adapted to cover both edges and means for removably securing the strip, the bottom side of the frame being grooved at its bottom edge to receive the strip which, with the edges of the cloth, is forced into the groove by said securing means.

8. The combination in a dust collecting screen of an open frame, cloth on the opposite sides of the frame covering said opening, supporting wires secured to the frame inside the cloth stretched across the opening for supporting the cloth, said wires being arranged to yield in the direction of their length to permit the tensioning of the cloth and means for expanding the frame to adjust the tension of the cloth and wires.

9. The combination in a dust collecting screen of an open frame, cloth on the opposite sides of the frame covering said opening, wires secured to the frame inside the cloth and stretched across the opening to support the cloth and means for adjusting the frame to tension said cloth and wires, said wires being arranged to yield to provide for said adjustment.

10. The combination in a dust collecting screen of an open frame, cloth on the opposite sides of the frame covering said opening, Wires secured to the frame inside the cloth stretched across the opening supporting the cloth, the frame having transverse members crossing the frame at intervals inside the Wires and supporting the same, the Wires being free to move in the direction of their length relatively to said transverse members, and means for expanding the frame to ti gliten the Wires and cloth.

11. The combination in a dust collector of a screen having a frame including a slotted upright on the clear air side, cloth covering the frame on both sides, means securing the edge of the cloth on one side to the slotted upright including a spacing strip removably secured to the frame and covering the edge of the cloth on that side, the next adj acent screen in the dust collector having a flap projecting therefrom adjacent to said spacing strip, said spacing strip being grooved on its edge which is disposed toward the clear air side of the screen and a fastening strip fitting in said groove and covering and securing the edge of the said flap, said flap thus secured serving to seal the screens on the clear air side.

12. The combination in a dust collector of a screen having a frame, including a slotted upright on the clear air side, cloth covering the frame on both sides, means securing the edge of the cloth on one side of the slotted upright, including a spacing strip removably secured to the frame and covering the edge of the cloth on that side, the next adj acent screen in the dust collector having a flap projecting therefrom on the clear air side and adjacent to said spacing strip, said spacing strip being grooved on its edge which is disposed toward the clear air side of the screen, a fastening strip fitting in said groove and covering and securing the edge of the said flap, said flap thus secured serving to seal the screens on the clear air side, said spacing strip and slotted uipright being rabbeted on their opposed surfaces to assist in securing the cloth.

13. The combination in a dust collector of a screen having a frame, including a slotted upright on the clear air side, cloth covering the frame on both sides, means securing the edge of the cloth on one side o'f the slotted upright, including a spacing strip removably secured to the frame and covering the edge of the cloth on that side, the next adjacent screen in the dust arrester having a flap projecting therefrom on the clear air side and adjacent to said spacing strip, said spacing strip being grooved on its edge which is dis posed toward the clear air side of the screen and a fastening strip fitting in said groove and covering and securing the edge of the said flap, said flap thus secured serving to seal the screens on the clear air side, said spacing strip and slotted upright being rabbeted on their opposed surfaces to assist in securing the cloth, and means for removably securing the remaining edges of the cloth.

14s The combination in a dust collector of screen members each comprising a frame with screen cloths secured to the opposite sides of the frame, means supporting the frames whereby they are spaced apart, spacing members secured to the screens on the clear air side, only partially closing the space and sealing flaps, one secured to each screen and means removably securing each said flap to the spacer of the next screen, sealing the space between the screen members on the clear air side.

15. In a dust collector, spaced screen members each screen member comprising a frame with screen cloth secured thereto, means for supporting the frame whereby they are spaced apart, each screen member having a flap on the clear air side and means removably securing said flap to the next screen, sealing the spaces between the screens on the clear air side.

16. In a dust collector, screen members spaced apart and means sealing the spaces between the screens on the clear air side, comprising areasof cloth removably secured to the screens of each pair of adjacent screens and securing means for said cloth comprising i strips and means removably securing the strips to the screen members.

17. In a dust collector, screen members spaced apart and means sealing the spaces between the screens on the clear air side, comprising areas of cloth removably secured to the two screens of each pair of adjacent screens, and securing means for said cloth comprising strips and means removably securing the strips to the screen members, the screens being grooved to receive the strips and the cloth, the latter underlying the strips in the groove.

18. The combination in a dust collector of a plurality of screen frames placed side by side and having screen cloths mount-ed on the frames and spaced apart in the assembled relation of the frames, the individual screen frames having adjustable compression members extending from side to side of the frame and abutting against the opposite sides of the frame from within, and means for adjusting the length of said tension members to expand the screens and apply tension to the cloth, said assembled collector apparatus being apertured adjacent the ends of said compression members and said adjusting means being accessiblelfor operation through the said apertures for the adjustment of the respective framesand the tensioning of the cloth. 7

19. The combination in a dust collector of a plurality of screens, each having a frame with screen cloth, and means for securing said cloth to the opposite sides of the frame, means for supporting the frames in a dust arrester and assembly, and means for adjusting each individual frame to change the area thereof to regulate the tension of the cloth, said means comprising a transverse rod extending across the frame intermediately thereof from one side to the other between the cloths, and having abutments at its opposite ends bearing outwardly against the frame members, and means accessible in the assembled relation of the screens to move one abutment to expand the frame and apply increased tension to the cloth.

Signed by me at Hagerstown, Maryland, this 25th day of March, 1929.

MORTON I. DORFAN. 

